Intermodal freight transport in Europe (by road, rail and sea ferry) requires containers of maximum internal volume and minimum tare weight. Current European regulations allow a maximum container length of 13.6 m and a maximum width of 2.5 m/2.55 m. This width can accommodate two rows of 1.2 m standard pallets which, after allowing for practical clearances, allows 40 mm or so at most for each of two side wall structures.
Swapbody containers of 13.6 m currently exist, these containers have corrugated steel sides which are specially strengthened at locations 12.2 m (40 feet) apart along the sides (ie at the xe2x80x9c40 feetxe2x80x9d location) to provide, in effect, 12.2 m (40 feet) posts. At the top of each 12.2 m (40 feet) post is a standard I.S.O. fitting (corner casting) which allows the container to be top-lifted by a known 12.2 m (40 feet) spreader with twistlock connectors. Also, a standard laden 1 2.2 m (40 feet) container may be stacked on top of such a container.
However, such containers suffer from a drawback that freight cannot be loaded or unloaded except through a rear end door, whereas the great majority of road trailers (of this size) are curtain sided, which has the great advantage of allowing side loading and unloading.
The roof structure of 13.6 m curtainside swapbody containers now in common use is relatively flimsy. This is necessitated by the requirements for maximum side aperture height, which limits the structural depth allowable for the roof (commonly no more than 100 mm approximately). For the same reason, the structural depth of the base has to be kept to a minimum (currently approximately 250 mm) which results in a very flexible base structure which deflects very significantly when under load.
It is therefore impractical to stack a laden 12.2 m (40 feet) unit on top of a 13.6 m curtainside container, nor can a laden 13.6 m curtainside unit be stacked on top of another container, since excessive base deflection would cause unacceptable loadings on the roof of the container underneath. Notionally, a rigid-walled 13.6 m unit could be stacked on a curtainside one, except that significant longitudinal racking forces would arise during transport and it is unlikely that the curtainside container could safely resist these longitudinal forces.
However, there is a strong demand, currently unsatisfied, for 13.6 m curtainside containers which also have the capability of being stacked laden and top-lifted. Top lifting equipment is readily available at most docksides and intermodal depots; whereas, grapple lifting or sling lifting equipment is not readily available, being very specialised. Ship to shore container cranes invariably have top lifting equipment and a Lift On Lift Off (LO-LO) operation is highly desirable for deck cargoes on short-sea ferries. Also, many ferries carry containers stacked two-high below decks on Maffi-type platforms/cassettes. These Maffi cassettes commonly have a capacity of 70,000 kg (70 tonnes) and are rolled on and off the ship (RO-RO) with special tractors. Currently, only a single curtainside container can be transported by this system, resulting in the waste of valuable ship space. In effect, an operator has to pay for two container slots, when moving only one container.
13.6 m curtainside containers currently have I.S.O. fittings (or similar lightweight versions) in their base structure at the 12.2 m (xe2x80x9c40 feetxe2x80x9d) locations. The purpose of these fittings is to allow twistlock connection of the container to a road chassis (trailer), a rail wagon or to a ship""s deck. If a full I.S.O. fitting were provided in the roof structure at each 12.2 m (xe2x80x9c40 feetxe2x80x9d) location, and the top and bottom 12.2 m (xe2x80x9c40 feetxe2x80x9d) fittings connected by a structural xe2x80x9cpostxe2x80x9d member, then the container would be top liftable and stackable. Unfortunately, such xe2x80x9cpostsxe2x80x9d would prevent satisfactory side loading and unloading of the container.
One manner for overcoming the difficulty would be to make the 40 feet posts removable, however, this presents a further difficulty in that the post is necessarily heavy and impractical to be removed safely by manpower. Also, it would not be easy to make a satisfactory connection to the container at the top of the post, since the top is a long way from the ground and therefore, not easily accessible.
It is an object of the present invention to at least mitigate the foregoing difficulties.
According to the present invention there is provided a freight container including a base, a roof, fitting means located on the roof for lifting the container and/or stacking a second container on the roof, and support means moveably mounted on the container, the support means being moveable between a load-bearing position for transferring a load between the fitting means and the base and a loading position in which the support means does not substantially impede loading and unloading of the freight container from a side of the container, wherein the support means is located on gate means (20) hingedly fixed to corner posts (3, 4) in corners of the container.
Conveniently, the support means is a substantially vertical strut.
Advantageously, locking means are provided for locking the support means in the support position.
Conveniently, two fitting means are mounted on the roof proximate a junction of the roof with a side wall of the container, the two fittings being separated by a predetermined distance less than a length of the side wall.
Preferably, the predetermined distance is 12.2 metres (40 feet).
Conveniently, a transverse roof beam is provided to connect fitting means located proximate opposed side walls.
In one embodiment, the present invention overcomes the above noted difficulties by mounting the removable 12.2 m (40 feet) posts on a hinged xe2x80x9cgatexe2x80x9d structure such that the whole structure can be swung out of the way, yet remain easily in control of the operator. Connections at the top and bottom of the 12.2 m (40 feet) post comprise a spigot and a socket system which automatically engages when the gate is swung xe2x80x9cshutxe2x80x9d. To assist engagement/disengagement the spigots and sockets are tapered.
In order to force the connections into engagement and to hold them securely engaged (also to force them out of engagement) standard door locking gear is used. This comprises a tubular shaft running from the top to the bottom of each xe2x80x9cgatexe2x80x9d. At the ends of the shaft are specially shaped claw-type cams which engage with matching cam-keepers fixed to the main structure. As the shaft is rotated (using a handle or lever near the bottom of the shaft, where it is easily accessible) the xe2x80x9cgatexe2x80x9d is forced shut and the spigot connections forced into engagement. The handle is then secured in the xe2x80x9cshutxe2x80x9d position and the top and bottom connections of the 12.2 m (40 feet) post are thereby secured. The first container may now be safely top lifted, also a second laden unit may be stacked on top of the first container.
The achievement of top lift and laden stacking capabilities does involve significant additional tare weight compared with similar containers which do not have these capabilities. The reasons for the extra weight are, of course, the weight of the 12.2 m (40 feet) posts themselves and the associated gate structure, also the weight of a substantial transverse roof beam which is needed to resist the eccentricity moments arising at the I.S.O. top lift fittings. The eccentricity occurs because the 12.2 m (40 feet) post (of necessity) is located close to the 2.5 m outer xe2x80x9cenvelopexe2x80x9d (so as to allow internal width for two 1.2 m pallets side by side) whereas the twistlocks come well inside the ISO 2.438 m xe2x80x9cenvelopexe2x80x9d. In addition, the complete structure, in particular the base structure, has to be heavier in order to comply with the international Container Safety Convention (CSC) which is legally obligatory for top liftable containers. In order to obtain CSC Certification the unit has to be tested to 2.0 R (where R equals the maximum gross rated mass) whereas the grapple and sling lifted units do not require CSC Certification, they merely have to comply when CEN standards for swapbodies which call for testing to 1.5 R only.